The influence of multiple fouling and cleaning cycles upon the membrane processing of lignosulphonates

Although the application of pressure-driven membrane technology continues to grow, fouling remains a major unsolved problem. Despite the success achieved with mechanical cleaning methods such as backfluushing and backshocking, chemical cleaning-in-place remains the major way to tackle fouling1–3. This paper investigates the relationship between fouling and cleaning processes, and how they influence each other over a number of operational cycles. Results are reported for the ultrafiltration of lignosulphonates, which simulates a real industrial filtration problem in the pulp and paper industry. Cleaningwas undertaken with both an acid and a commercial aqueous cleaning formulation. Results are presented which show that cleaning performance is strongly dependent upon the nature of the foulant. Results also illustrate the importance of examining membrane performance over several fouling and cleaning cycles.